Analyte detection in physiological fluids, e.g. blood or blood-derived products, is of ever increasing importance to today's society. Analyte detection assays find use in a variety of applications, including clinical laboratory testing, home testing, etc., where the results of such testing play a prominent role in diagnosis and management in a variety of disease conditions. Analytes of interest include glucose for diabetes management, ketones, cholesterol (including HDL, LDL, and/or triglycerides), hemoglobin A1C, and the like. In response to this growing importance of analyte detection, a variety of analyte detection protocols and devices for both clinical and home use have been developed.
One type of method that is employed for analyte detection is an electrochemical method. In such methods, an aqueous liquid sample is placed into a sample reaction chamber in a test strip, in this case an electrochemical cell, including two electrodes, i.e. a first and second electrode, where the electrodes have an impedance, which renders them suitable for amperometric measurement. The component to be analyzed is allowed to react directly with an electrode, or directly or indirectly with a mediator to form an oxidizable (or reducible) substance in an amount corresponding to the concentration of the component to be analyzed, i.e. analyte. The quantity of the oxidizable (or reducible) substance present is then estimated electrochemically and related to the amount of analyte present in the initial sample.
One strategy which may be used to quantify the analyte is to allow the analyte to become substantially depleted within the electrochemical cell before electrochemically measuring an oxidizable (or reducible) substance. However, under certain conditions this process may require an extended time period to reach depletion. Other strategies for quantifying the analyte rely on a shorter waiting period. For example, an oxidation current (or reduction current) can be measured over a time period less than that required for complete depletion and the concentration is calculated by extrapolating the collected data. While shorter calculation procedures meet the desire for expedient analysis (especially in the case of glucose monitoring) such methods may lack the desired accuracy. Therefore, it would be desirable to develop a method for quickly and accurately measuring the concentration of an analyte in an electrochemical cell.